Field of the Invention
The present invention relates to a heat pump system for a vehicle, and more particularly, to a heat pump system for a vehicle having a complex valve device which includes: a three-way valve, an on-off valve, expansion means and connection blocks are formed integrally with one another, the three-way valve part being connected to the refrigerant circulation line of an inlet of the exterior heat exchanger such that the refrigerant selectively bypasses the exterior heat exchanger, the on-off valve part being connected to an inlet of the bypass line to open and close the bypass line, the connection blocks connecting the three-way valve part and the on-off valve part with the refrigerant circulation line of an outlet of the exterior heat exchanger to communicate with each other, and expansion means being connected to an inlet of the three-way valve part to selectively expand refrigerant discharged from an interior heat exchanger
Background Art
In general, an air conditioner for a vehicle includes a cooling system for cooling the interior of the vehicle and a heating system for heating the interior of the vehicle. At an evaporator side of a refrigerant cycle, the cooling system converts air into cold air by heat-exchanging the air passing outside an evaporator with refrigerant flowing inside the evaporator so as to cool the interior of the vehicle. At a heater core side of a cooling water cycle, the heating system converts air into warm air by heat-exchanging the air passing outside the heater core with cooling water flowing inside the heater core so as to heat the interior of the vehicle.
In the meantime, differently from the air conditioner for the vehicle, a heat pump system which can selectively carry out cooling and heating by converting a flow direction of refrigerant using one refrigerant cycle has been applied. For instance, the heat pump system includes two heat exchangers: one being an interior heat exchanger mounted inside an air-conditioning case for heat-exchanging with air blown to the interior of the vehicle; and the other one being an exterior heat exchanger for heat-exchanging outside the air-conditioning case, and a direction-adjustable valve for changing a flow direction of refrigerant. Therefore, according to the flow direction of the refrigerant by the direction-adjustable valve, the interior heat exchanger serves as a heat exchanger for cooling when the cooling mode is operated, and serves as a heat exchanger for heating when the heating mode is operated.
Various kinds of the heat pump system for the vehicle have been proposed, and FIG. 1 illustrates a representative example of the heat pump system for the vehicle.
As shown in FIG. 1, the heat pump system for the vehicle includes: a compressor 30 for compressing and discharging refrigerant; a high pressure heat exchanger 32 for radiating heat of the refrigerant discharged from the compressor 30; a first expansion valve 34 and a first on-off valve 36 mounted in parallel for selectively passing the refrigerant passing through the high pressure heat exchanger 32; an outdoor heat exchanger 48 for heat-exchanging the refrigerant passing through the first expansion valve 34 or the first on-off valve 36 outdoors; a low pressure heat exchanger 60 for evaporating the refrigerant passing through the outdoor heat exchanger 48; an accumulator 62 for dividing the refrigerant passing through the low pressure heat exchanger 60 into a gas-phase refrigerant and a liquid-phase refrigerant; an inside heat exchanger 50 for heat-exchanging refrigerant supplied to the low pressure heat exchanger 60 with refrigerant returning to the compressor 30; a second expansion valve 56 for selectively expanding the refrigerant supplied to the low pressure heat exchanger 60; a bypass line 58a mounted in parallel with the second expansion valve 56 and the low pressure heat exchanger 60 for connecting an outlet of the outdoor heat exchanger 48 with an inlet of the accumulator 62; and a second on-off valve 58 for opening and closing the bypass line 58a. 
In FIG. 1, the reference numeral 10 designates an air-conditioning case in which the high pressure heat exchanger 32 and the low pressure heat exchanger 60 are embedded, the reference numeral 12 designates a temperature-adjustable door for controlling a mixed amount of cold air and warm air, and the reference numeral 20 designates a blower mounted at an inlet of the air-conditioning case.
According to the heat pump system having the above structure, when a heat pump mode (heating mode) is operated, the first on-off valve 36 and the second expansion valve 56 are closed, and the first expansion valve 34 and the second on-off valve 58 are opened. Moreover, the temperature-adjustable door 12 is operated as shown in FIG. 1. Accordingly, the refrigerant discharged from the compressor 30 passes through the high pressure heat exchanger 32, the first expansion valve 34, the outdoor heat exchanger 48, a high pressure side 52 of the inside heat exchanger 50, the second on-off valve 58, the accumulator 62, and a low pressure side 54 of the inside heat exchanger 50 in order, and then, is returned to the compressor 30. That is, the high pressure heat exchanger 32 serves as a heater and the outdoor heat exchanger 48 serves as an evaporator.
When an air-conditioning mode (cooling mode) is operated, the first on-off valve 36 and the second expansion valve 56 are opened, and the first expansion valve 34 and the second on-off valve 58 are closed. Furthermore, the temperature-adjustable door 12 closes a passage of the high pressure heat exchanger 32. Therefore, the refrigerant discharged from the compressor 30 passes through the high pressure heat exchanger 32, the first on-off valve 36, the outdoor heat exchanger 48, the high pressure side 52 of the inside heat exchanger 50, the second expansion valve 56, the low pressure heat exchanger 60, the accumulator 62, and the low pressure side 54 of the inside heat exchanger 50 in order, and then, is returned to the compressor 30. That is, the low pressure heat exchanger 60 serves as an evaporator and the high pressure heat exchanger 32 closed by the temperature-adjustable door 12 serves as a heater in the same way as the heat pump mode.
Moreover, besides the bypass line 58a for bypassing the circulating refrigerant, the heat pump system for the vehicle includes a branch line (not shown) for branching a fixed amount of the refrigerant and supplying the refrigerant to a specific part; a three way valve (not shown) mounted on a line, in which the refrigerant flows, for changing a flow direction of the refrigerant; on-off valves 36 and 58 for regulating a flow of the refrigerant; and expansion valves 34 and 56 for expanding the refrigerant.
However, the conventional heat pump system for the vehicle has several disadvantages in that the structure of refrigerant lines (pipes) is complicated because pipes such as the bypass line 58a and the branch line, the three way valve, the on-off valves 36 and 58 and the expansion valves 34 and 56 are closely arranged inside a small engine room, in that the heat pump system needs connection blocks (not shown) for connecting the refrigerant lines (pipes) with each other, and in that the heat pump system occupies a wide space inside the small engine room and is deteriorated in workability and fuel efficiency due to excessive weight because the valves are separately mounted.